fix: Fetch API version validation and ListOffsets v2 parsing

- Updated Fetch API to support v0-v11 (was v0-v1)
- Fixed ListOffsets v2 request parsing (added replica_id and isolation_level fields)
- Added proper debug logging for Fetch and ListOffsets handlers
- Improved record batch construction with proper varint encoding
- Cross-client Produce compatibility confirmed (kafka-go and Sarama)

Next: Fix Fetch v5 response format for Sarama consumer compatibility

test/kafka/kafka_go_produce_only_test.go

@@ -0,0 +1,45 @@
+package kafka
+
+import (
+	"context"
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/segmentio/kafka-go"
+	"github.com/seaweedfs/seaweedfs/weed/mq/kafka/gateway"
+)
+
+func TestKafkaGo_ProduceOnly(t *testing.T) {
+	// Start gateway
+	gatewayServer := gateway.NewServer(gateway.Options{Listen: "127.0.0.1:0"})
+	go func() {
+		if err := gatewayServer.Start(); err != nil {
+			t.Errorf("Failed to start gateway: %v", err)
+		}
+	}()
+	defer gatewayServer.Close()
+
+	time.Sleep(100 * time.Millisecond)
+
+	host, port := gatewayServer.GetListenerAddr()
+	addr := fmt.Sprintf("%s:%d", host, port)
+		topic := "kgo-produce-only"
+	gatewayServer.GetHandler().AddTopicForTesting(topic, 1)
+
+	w := &kafka.Writer{
+		Addr:         kafka.TCP(addr),
+		Topic:        topic,
+		Balancer:     &kafka.LeastBytes{},
+		BatchTimeout: 50 * time.Millisecond,
+	}
+	defer w.Close()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	err := w.WriteMessages(ctx, kafka.Message{Key: []byte("k"), Value: []byte("v")})
+	if err != nil {
+		t.Fatalf("kafka-go produce failed: %v", err)
+	}
+}

test/kafka/sarama_e2e_test.go

@@ -67,9 +67,50 @@ func TestSaramaE2EProduceConsume(t *testing.T) {
 		t.Logf("✅ Produced message %d: partition=%d, offset=%d", i, partition, offset)
 	}
 
-	// Temporarily skip consumer until Fetch batches are finalized
-	t.Logf("Skipping consumer verification for now (Fetch under construction)")
-	t.Logf("🎉 SUCCESS: Sarama E2E (produce-only) completed! Produced %d messages", len(messages))
+	t.Logf("=== Testing Sarama Consumer ===")
+
+	// Create consumer
+	consumer, err := sarama.NewConsumer([]string{brokerAddr}, config)
+	if err != nil {
+		t.Fatalf("Failed to create consumer: %v", err)
+	}
+	defer consumer.Close()
+
+	// Get partition consumer
+	partitionConsumer, err := consumer.ConsumePartition(topicName, 0, sarama.OffsetOldest)
+	if err != nil {
+		t.Fatalf("Failed to create partition consumer: %v", err)
+	}
+	defer partitionConsumer.Close()
+
+	// Consume messages
+	consumedCount := 0
+	timeout := time.After(5 * time.Second)
+
+	for consumedCount < len(messages) {
+		select {
+		case msg := <-partitionConsumer.Messages():
+			t.Logf("✅ Consumed message %d: key=%s, value=%s, offset=%d",
+				consumedCount, string(msg.Key), string(msg.Value), msg.Offset)
+
+			// Verify message content matches what we produced
+			expectedValue := messages[consumedCount]
+			if string(msg.Value) != expectedValue {
+				t.Errorf("Message %d mismatch: got %s, want %s",
+					consumedCount, string(msg.Value), expectedValue)
+			}
+
+			consumedCount++
+
+		case err := <-partitionConsumer.Errors():
+			t.Fatalf("Consumer error: %v", err)
+
+		case <-timeout:
+			t.Fatalf("Timeout waiting for messages. Consumed %d/%d", consumedCount, len(messages))
+		}
+	}
+
+	t.Logf("🎉 SUCCESS: Sarama E2E test completed! Produced and consumed %d messages", len(messages))
 }
 
 func TestSaramaConsumerGroup(t *testing.T) {